<?xml version="1.0" encoding="utf-8"?>
 <grammar xmlns="http://relaxng.org/ns/structure/1.0">
   <start>
     <element name="library">
       <oneOrMore>
         <element name="book">
           <attribute name="id"/>
           <attribute name="available"/>
           <element name="isbn">
             <text/>
           </element>
           <element name="title">
             <attribute name="xml:lang"/>
             <text/>
           </element>
           <zeroOrMore>
             <element name="author">
               <attribute name="id"/>
               <element name="name">
                 <text/>
               </element>
               <element name="born">
                 <text/>
               </element>
               <optional>
                 <element name="dead">
                   <text/>
                 </element>
               </optional>
             </element>
           </zeroOrMore>
           <zeroOrMore>
             <element name="character">
               <attribute name="id"/>
               <element name="name">
                 <text/>
               </element>
               <element name="born">
                 <text/>
               </element>
               <element name="qualification">
                 <text/>
               </element>
             </element>
           </zeroOrMore>
         </element>
       </oneOrMore>
     </element>
   </start>
 </grammar>
